initial drop of a plugin for creating Live CD images with lmc

This is actually a general purpose plugin for using one base image to
modify another to generate a target image.  The initial reason for
creating it was to allow running livemedia-creator in a controlled
environment but it can theoretically be used for other things.
fix typo from manual rebase/merge
Merge pull request #301 from aeolusproject/feature/livecd_plugin_merge

initial drop of a plugin for creating Live CD images with lmc